The present invention relates to a braking device for use with a vehicle which moves along a surface, the braking device being operated by means external to the vehicle, and particularly but not exclusively to a braking device for use with a wheeled trolley or cart to deter its removal from a designated area.
A particular problem with supermarket-type shopping trolleys or carts is the removal of these trolleys or carts from designated areas, such as the supermarket and/or its car park. Although various systems have been proposed for placing physical obstructions such as grids and/or narrow stalls at the exit points from these designated areas, which obstacles are intended to interact with the trolley's castor wheels or with the trolley itself to deter its removal, these known systems are easily overcome and are also unsuitable for certain applications, such as vehicle entrances for supermarket car parks.
A braking device designed to overcome these problems is described in International Patent Application No. WO92/15476. The device is designed to be activated as it passes over a member or area of magnetic material to cause a braking member to be applied to the ground to impede the trolley's continued movement. The braking device is conveniently associated with a castor wheel of the trolley. However, the environment of dust and heavy knocks which a trolley castor wheel has to withstand produces a weakness and unreliability in the locking and unlocking of this device. The present invention relates to an improvement of the type of device described in the above referred-to application.